Investigation on the exit phase controls for emergency vehicle preemption

Abstract

Many traffic signal control systems used in the U.S. have Emergency Vehicle Preemption (EVP) systems that change traffic signals to clear an intersection for emergency vehicles. However, one of the challenges of implementing EVP under coordinated-actuated signal systems is selecting the best recovery method at the end of preemption such that disruptions to normal traffic signal operations may be minimized. To this end, there have been lots of research efforts which have compared the performances of various transition methods after EVP operations using microscopic traffic simulation models, Hardware-in-the-loop Simulations (HILS) or softwarein-the-loop simulations (SILS). However, few attempted to implement exit phase controls during the EVP operations, which is available in recent advanced traffic controllers such as the ASC/3-2100 traffic controller. This paper was intended to report the evaluation results of two types of exit phase control -(i) fixed exit phase control and (ii) dynamic exit phase control during EVP operations. The evaluation was conducted using a HILS on an urban corridor including four coordinated-actuated signals along Lee Jackson Memorial Highway in Chantilly, Virginia. The evaluation results indicated that (i) the use of fixed exit phase control should be considered in the development of EVP strategies as it is able to minimize disruptions due to the EVP operation, and (ii) the dynamic exit phase control is capable to give an additional benefit during EVP operations. In the evaluation, the fixed and dynamic exit phase control reduced network-wide average delay time in seconds per vehicle to 2.8% and 4.5% over no exit phase control case, respectively.

A Collaborative Control Framework: Achieving Emergency Vehicle Priority While Minimizing Negative Impact on Ordinary Vehicles at Signalized Intersection

“…While this extreme approach achieves favorable EV performance, to a signifcant impact on OVs approaching from conficting directions. Tis method has been widely employed as a benchmark in previous studies [6,10].…”

“…Currently, research on the priority of EV pass through intersection areas can be classifed into three categories. Te frst category involves greedy signal preemption to prevent obstructions by the red phase [6,7]. Many studies employ devices like RFID and video to detect EV presence.…”

“…m . Te process is modeled through the equations (4)-(6). Te time range for the activation of DEL, is determined based on two scenarios: ① When EV encounters hindrance from OVs.…”

An emergency vehicle traffic signal preemption system considering queue spillbacks along routes and negative impacts on non‐priority traffic

“…To address this issue, Qin [43] and Qin and Khan [44] proposed a two-phase preemption algorithm that mitigates the negative impacts caused by signal preemption while restoring signals to normal operations. Yun et al [45] presented a rule-based method, and Oza and Chantem [46] proposed an optimization approach, both aimed at alleviating the impacts of preemption. Asaduzzaman and Vidyasankar [47] utilized transit signal priority (TSP) techniques to achieve the same objective.…”

Development of Degree-of-Priority Based Control Strategy for Emergency Vehicle Preemption Operation

“…Haghani et al [12] concentrated on developing an optimization model for developing flexible dispatching strategies that take the advantage of available real-time travel time information. In recent years, Yun et al [13,14] have optimized the exit phase controls for emergency vehicle preemption and compared the emergency vehicle preemption methods with a hardware-inthe-loop simulation. He et al [15] presented a heuristic algorithm for traffic signal control with simultaneous multiple priority requests at isolated intersections in the context of vehicle-to-infrastructure communications being available on priority vehicles, and the method could reduce average bus delay in congested conditions by about 50%.…”